Non-jamming drive actuator



June 10, 1958 c DESMOND 2,837,930

NON-JAMMING DRIVE ACTUATOR Filed March 20, 1956 3 Sheets-Sheet 1 I=l Flfig WZ4%MM, FF 5" i J s l imp June W, 1958 c. F. DESMOND NQN-JAMMINGDRIVE ACTUATOR Filed March 20, 1956 5 Sheets-Sheet 2 .257 V'EIY far(1445155 F flay/vamp Unite States 2,337,930 Patented June 10, 1958 FleeNON-JAMMING DRIVE ACTUATOR Charles F. Desmond, Wiiliamsville, N. Y.,assignor to Houdaille Industries, Inc., Detroit, Mich, a corporation ofMichigan Application March 20, 1956, Serial No. 572,726

1 Claim. (Cl. 74-4243) This invention relates generally to mechanicalmovements and more particularly relates to a screw-type actuator of thetype having load-release means or socalled free wheeling whereby theoperative components of the mechanism will be released at positionscorre sponding to the end limit positions of relative movement.

ltis an object of the present invention to provide an improvedmechanical movement incorporating loadre lease means.

Another object of the present invention is to provide an improvedscrew-type actuator having a free wheeling characteristic at the endlimit positions of travel.

Another object of the present invention is to provide a new andimprovedactuator combining a spring clutch with a screw-type actuator.

Another object of the present invention is to provide a screw actuatorembodying a spring clutch wherein a single spring can be utilized andmay be selectively inactivated by stop means at either end of theactuating device.

Another object of the present invention is to provide actuating meansincorporating a reduced number of simplified parts which are easy tofabricate and which are rugged and durable in use.

Many other features, advantages and additional obiects of the presentinvention will become manifest to those versed in the art upon makingreference to the detailed description which follows and the accompanyingsheets of drawings in which a preferred structural embodiment of ascrew-type actuator incorporating the principles of the presentinvention is shown by way of illustrative example.

On thedrawings:

Figure l is a plan elevational view of an automotive seat adjustermechanism incorporating a plurality of actuating units embodying theprinciples of the present invention;

Figure 2 is an end elevational view taken substantially on line II-Il ofFigure 1 illustrating details of the linkage and slide track supportmeans provided for the seat adjuster mechanism of Figure l;

Figure 3 is a cross-sectional view taken generally on line III--III ofFigure 1 and has parts broken away and parts shown in cross-section toillustrate additional details of structure of a representative actuatingunit incorporating the principles of the present invention;

Figure 4 is an enlarged cross-sectional view similar to Figure 3 butshowing additional details of construction of the actuator unit;

Figure 5 is a fragmentary cross-sectional view with parts shown inelevation taken generally on line V-V of Figure l;

Figure 6 is an end eievational view of the actuator unit shown in Figure4;

Figure 7 is an elevational view of the nut member and the coil springmeans of the device of Figure 4; and

Figures 8 a'nd9 are end elevational views of opposite ends of t .estructure of Figure 7.

As shown on the drawings:

The screw-type actuator of the present invention comprises a mechanicalmovement of general utility, however, in order to best illustrate theconstruction and use of the actuator, a representative application ofthe actuator, is referred to for the purposes of this disclosure,namely, a seat-adjuster mechanism for an automotive vehicle as showngenerally in Figure 1 by the reference numeral 10. A seat cushion 11 iscarried by a generally rectangular frame 12 and is adapted to beadjustably carried on a relatively stationary support 13 which mayconveniently comprise the body portion of an automobile. Accordingly, atopposite ends of the frame 12, there is provided slide track means 14-secured to the underside of the frame 12 by means of a front bracket 16and a rear bracket 17. Although not all of the structural elements ofthe slide track mechanism are necessary to a proper understanding of theprinciples of the present invention, those versed in the art willappreciate that components of the slide track means 14 can be carried bythe support 13 through bracket means which are indicated hereingenerally by the reference numeral (Figure 2). One of the actuator unitsof the present invention indicated generally by the reference A(Figure 1) is provided to selectively move the seat frame 12 forwardlyand backwardly between end limit positions of forward and backwardadjustment.

For further effecting either a platform lift of the seat frame 12 or toeffect selective tilting of the seat frame 12, a linkage assembly isprovided for accommodating vertical movements of the frame 12 as Well asforward and backward movements permitted by the slide track 14. Thusthere is provided a bracket 18 at the front of the seat adjustermechanism 19 having a pivot 19 carrying a bell crank 2% including afirst arm 21 and a second arm 22.

At the rear of the mechanism, there is provided a bracket 23 which isfastened to the support 13 having a pivot mounting 2d pivotallysupporting a pivot bracket 26 which, in turn, provides a pivot mounting27 to which is connected in pivotal assembly one arm 28 of a bell crank29, the second arm of the bell crank 29 being indicated at 30. A guidebracket 31 fastened to the bracket means 15 provides an elongated slotor guideway 32 in which is received a roller 33 supported by the bellcrank 29.

A pivotal connection indicated at 34 (Figure 2) connects the arm 30 ofthe bell crank 29 to a bar member 36 extending towards the forward endof the seat adjuster mechanism 10 and pivotally connected at its otherend to the arm member 22 of the bell crank 29 as indicated at 37.

The arm 21 of the bell crank carries a cross rod 38 which is also shownin Figure 3, the cross rod 38 being connected at opposite ends to thebracket means 15.

A coil spring 39 is connected to the crank arm of the bell crank 29 asat 40 and is connected as at 41 to the support 13.

As shown in Figure l, a screw actuator unit B is provided for effectinga tilting operation of the mechanism 10 and an actuator unit indicatedat C is provided for effecting a selective platform lift adjustment ofthe mechanism 10.

Referring briefly to the operational characteristics of the three unitsA, B and C, it will be noted that the unit A has relatively extensiblemembers, one of the members being pivotally connected to a supportbracket carried by the support structure 13. The other extensible memberis connected to the seat frame 12 by means of a bracket 42 having a pin42a extending therethrough. Thus, upon relative extension or contractionof the extensible elements, movement is produced between the supportstructure 13 and the frame 12,

tions 62 and 63 at opposite ends thereof.

The unit C is connected to a bracket 43 carried by the support structure13 at one end and includes a bracket 44 connected to the cross bar 38 atthe other end. Thus, upon relative extension or contractual adjustmentof the extensible members of the unit C, the cross bar 38 is movedwithin a confined path determined by the bell crank since the cross bar33 is supported by the crank arms 21 of the supporting structures atopposite sides of the seat mechanism 10.

Moreover, when the bell crank 20 is actuated, the crank arm 22 willtransmit relative movement through the bar member 36 to the crank arm ofthe bell crank 29, whereupon the entire bell crank 29 will pivot aroundthe pivot mounting 27 and both ends of the seat frame 12 will beelevated in unison to afford a platform lift adjustment.

The tilting unit B is pivotally supported by a bracket member 46 at oneend and is pivotally connected to a second bracket indicated at 48. Thebracket 46 has a pivotal connection as at 49 with the lever arm 58connected to the cross rod 38. The bracket 48 is connected to a secondcross rod indicated at 51 which is connected at opposite ends tocorresponding pivot frame members previously indicated at 26. Thus,whenever relative extension occurs through actuation of the tilting unitB, the cross rod 51 will operate to pivot the pivot bracket 26 about theaxis of the pivot mounting 24, which incidentally, is coincident withthe axis of the cross rod 51 thereby swinging the pivot mounting 27 andproducing a corresponding movement of the bell crank 29 and specificallythe roller 33. During this tilting operation, the pivot mounting 34 isrestrained since the bar member 36 is connected thereto and is in turnconnected to the bell crank member 20. The tilting unit is carried bythe bracket means 46, however, and since the bracket means 46 isconnected to the cross rod 38, no pivotal movement of the bell crank 20occurs thereby insuring a tilting movement of the bell crank 29 aboutthe axis 24 and a consequent tilting of the seat frame 12.

Although three separate actuator units are illustrated in connectionwith the seat adjuster mechanism 10, it will be appreciated that each ofthe units, A, B and C can be constructed along substantially similarlines. Accordingly, only one of the units will be described in detail inconnection with the disclosure of the structural and functional featuresof the screw-type actuator of the present invention.

The actuator unit B comprises inner and outer parts provided by a nutmember and a retainer sleeve 61, respectively. The nut member 60 is agenerally cylindrical element having a peripheral outer surface and isparticularly characterized by reduced diameter por- At the reduced end63, there is'mountcd a radially outwardly extending flange 64 which isfastened in firm assembly to the nut member 60 as by means of weldingindicated at At the reduced end 62, a fiange providing member 67 isfastened in firm assembly with the nut member 60 by means of a set screw68.

The retainer sleeve 61 is a sleeve-like element having an open-endedbore providing a cylindrical inner surface 69. The outer peripheralsurface of the retainer sleeve 61 is threaded as at 70 and thereby maybe threadedly assembled in the end of a tubular member 71 adapted to beconnected to the means to be actuated. T hus. in the specificapplication of the actuator unit B, as shown in Figure 3, the tubularmember 71 is threadedly connected to a second tubular member 73 and isretained in locked position thereon by means of a lock nut 74. Thetubular member 73 has a bracket 76 connected thereto which, in turn, ispivoted as at 77 to the lever arm 48. To secure 'ly lock the retainersleeve 61 in firm assembly with the tubular member 71, one or more setscrews 73 are threaded through the tubular member 71 into lockingengagement with the retainer sleeve 61.

The inner surface 69 of the sleeve member 61 is substantiallycoextensive with the peripheral surface 65 provided on the nut member60. Interconnecting means are interposed between the confrontingsurfaces 69 and 65 to provide a limited frictional connection betweenthe parts. In accordance with the principles of the present invention,the interconnecting means takes the form of a helically wound coilspring 30 having a plurality of coils arranged with the coiling axiscoaxial with respect to the axis of the nut member 60 and encircling theperipheral surface 65 thereof. The normal self-energizing action of thecoil spring 80 tending to unwind the springs results in a frictionalengagement between the peripheral surfaces herein indicated at 81 of thespring coils with the engagement surface 69. Whenever such engagementoccurs, the nut member 60 is held against relative rotation with respectto the retainer sleeve 61.

As is particularly shown in Figures 6 and 9, the flange member 64 isparticularly characterized by the formation therein of a notch or slot82, shoulders being indicated at 83 and 84 at opposite sides of theslot. Confined within the slot for limited movement prescribed by theshoulders 83 and 84, is a tang 86 which is angularly offset at one endof the coil spring 80.

The flange 67 provided at the opposite end of the nut member 60 has anotch or slot 87 formed therein, shoulders 88 and 89 being provided atopposite sides of the slot 87 and serving to confine a tang 90 angularlyoffset at the opposite end of the coil spring 80.

In accordance with the principles of the present invention, a screwshaft 91, provided on its peripheral surface with a helical thread 92,is threaded through the nut member 60 and upon relative rotation betweenthe screw shaft 91 and the nut member 60, the two parts are axiallymoved with respect to one another.

When the spring coils 80 couple the nut member 60 to the retainer sleeve61, the axial advance of the nut results in the translatable adjustmentof the tubular member 71 and the corresponding means to be actuatedassociated therewith.

By virtue of the structure thus provided, the drive nut or nut member 60is threaded on the mating drive screw or screw shaft 91 and is free torotate thereupon. Interposed between the driven collar or retainersleeve 61 and the nut member 68 is the helical spring 80 with theoppositely extending axial tangs 86 and 90. The rotation of the spring80 is limited by the shape of the notches or slots 82 and 87 in thethrust rings or flanges 64 and 67, in other words, by the spacingdimension between the circumferentially spaced shoulders 83 and 84 and88 and 89, respectively. The thrust rings or flanges 64 and 67 alsolimit the axial motion of the retainer sleeve 61 since it will be notedthat the end surfaces 61a and 61b closely confront the adjoining sidefaces of the flange members 67 and 64, respectively.

It is contemplated in accordance with the principles of the presentinvention that the screw shaft 91 be provided with stop means at axiallyspaced or longitudinally separated points corresponding to the limits ofadjustment contemplated in accordance with the specific actuatorapplication. In the present embodiment, there is provided a stop pin 94at one end of the screw shaft 91 and a second stop pin 96 (Figure 3) atthe other end of the screw shaft 91.

When the screw shaft 91 is rotated, the nut is axially advanced untilone of the stop pins 94 or 96 engages a corresponding spring tang 90 or86. Such engagement will tend to rotate the entire coil spring 80,however, the opposite spring tang, for example, as shown in Figure 4,the spring tang 86, will then engage the shoulder 84 on itscorresponding thrust ring or flange 64 whereupon further rotation of thespring will reduce the outside diameter of the coils, therebycontracting the bearing surfaces 81 and reducing the radial couplingforce between the peripheral surfaces '81 of the coil spring 80 andthesurface 60 of the retainer ring 61. This action declutches the spring80 from the driven collar or retainer sleeve 61 whereupon the screwshaft 91 together with the nut member 60, the thrust rings or flanges 64and 67 and the coil spring 80 will revolve as a unit with respect to thetubular member 71 and the retainer ring 61 with no further relativeaxial motion between the nut member 60 and the screw shaft 91.

As shown in Figure 3, the screw shaft 91 has an extension 101 journalledin a pair of spaced bearings 102 and 103 carried in a gear box 104. Agear 106 is carried by the extension 101 and meshes with a worm 107attached to the power take-off shaft 108 of an electric motor 109mounted in firm assembly on the gear box 104. A suitable mountingbracket 110 is provided to carry the gear box 104 and the electric motor109 in pivotal assembly, for example, on the bracket 46 in the case ofthe unit B, the pivot mounting being indicated at 111. As shown inFigure 5, the power take-off shaft 108 is provided with bearing supportas at 112 on the free end thereof adjacent the worm 107.

In operation, upon rotation of the screw shaft 91, with no stop means inengagement with the coil spring means, the tendency of the nut 60 torotate in the same direction as the screw shaft 91, due to the torqueresulting from friction between the nut 60 and the screw shaft 91 isresisted by the self-energizing action of the coil spring means, whichin unwinding in the confined space provided between the walls of thethrust or retainer member 61 and the adjoining space expands and exertsa radial force against the thrust and retainer member 61, effectivelypreventing the nut 60 from rotating within the thrust and retainermember 61. The thrust and retainer member 61, then transmits the axialmotion of the nut to a device to be translated.

When the nut 60 reaches a stop pin 94 or 96 which is a limit of theaxial motion, the projected end 90 or 86 of the spring 80 engages acorresponding pin 94 or 96 whereupon the spring 80 will wind-up,decreasing the radial force between the abutting surfaces whereupon thenut 60 will rotate within the retainer 61 at the same velocity as thescrew shaft 91.

Although various minor modifications might be suggested by those versedin the art, it should be understood that I wish to embody within thescope of the patent warranted hereon all such modifications asreasonably and properly come within the scope of my contribution to theart.

I claim as my invention: 1

A translation adjuster comprising a motor having a gear box housing,means for pivotally securing said gear box housing and said motor on astationary support, a screw shaft projecting out of said gear boxhousing and being rotatably driven in selected angular direction by saidmotor, a pair of axially spaced stop pins on said screw shaft, a nutmember threaded on said screw shaft and movable between said stop pinsupon relative rotation between said nut member and said screw shaft,frame means to be translatably adjusted including a nonrotatable thrustmember circumjacent said nut member, and a spring clutch between saidcollar and said nut member comprising a coil spring having the coilingaxis coaxial with the axis of said nut member and said screw shaft andhaving oppositely extending tangs on the ends thereof, a thrust ring ateach end of said nut member, each thrust ring having a slot formedtherein confining a corresponding tang for limited angular movement, theself-energizing action of said coil spring effecting frictionalengagement between the peripheral surfaces of said coils and saidcollar, said stop pins on said shaft engaging said tangs when said tangsare moved to limit positions by relative axial movement of said nutmember and said screw shaft to wind up said coil spring, therebydecreasing the diameter of the coils thereof and permitting rotation ofsaid nut member relative to said thrust member and together with saidscrew shaft at the limit positions.

References Cited in the file of this patent UNITED STATES PATENTS2,345,182 Corber Mar. 28, 1944 2,446,393 Russell Aug. 3, 1948 2,540,009Pepper Jan. 30, 1951 2,660,028 Geyer Nov. 24, 1953 2,765,024 BrundageOct. 2, 1956

